1. Field of the Invention
Embodiments of the invention relate generally to semiconductor memory devices and a memory systems including semiconductor memory devices. More particularly, embodiments of the invention relate to semiconductor memory devices and related systems having improved operating speed and reliability relative to conventional devices and systems.
2. Description of Related Art
Nearly all modern electronic devices include some form of volatile or nonvolatile semiconductor memory. Examples of volatile semiconductor memories include dynamic random access memory (DRAM) and static random access memory (SRAM), and examples of nonvolatile semiconductor memories include NOR flash memory, NAND flash memory, and phase change random access memory (PRAM).
In general, volatile memories tend to be cheaper, faster, and more densely integrated than nonvolatile memories. However, volatile memories lose stored data when disconnected from an external power source. As a result, nonvolatile memories are becoming an increasingly popular choice for providing data storage in a number of contemporary devices such as portable electronic devices.
Because of the increasing popularity of nonvolatile memories, significant efforts have been dedicated to improving the performance and reliability of nonvolatile memories.